1. Field of the Invention
The present invention relates to a light emitting device and a display unit using it, and more particularly such a self-luminous type light emitting device such as an organic light emitting device and a display unit using it.
2. Description of the Related Art
In these years, as a display unit instead of a liquid crystal display, an organic electroluminescence display which uses organic light emitting devices has been noted. The organic electroluminescence display has characteristics that its visual field angle is wide and its power consumption is low since it is a self-luminous type display. The organic electric field light emitting display is also thought of as a display having sufficient response to high-definition high-speed video signals, and is under development toward the practical use.
FIG. 1 shows a construction of a conventional organic light emitting device. This organic light emitting device has, for example, a structure wherein a transparent electrode 112 and an organic layer 113 are layered in this order on a substrate 111 made of an insulating material such as glass from the substrate 111 side. In the organic layer 113, an electron hole transport layer 113A and a light emitting layer 113B are layered in this order from the substrate 111 side. Lights generated in the light emitting layer 113B are extracted from the substrate 111 side.
However, in such a conventional organic light emitting device, a peak width of a spectrum of the extracted light is wide, and particularly, peak wavelengths of green and blue lights are considerably shifted. Therefore, there is a problem that a color reproduction range sufficient to display television picture cannot be obtained.
Therefore, trials to control lights generated in a light emitting layer, for example, a trial to improve color purity of light emitting colors and light emitting efficiency by introducing a resonator structure to the organic light emitting device have been made (for example, refer to International Publication No. 01/39554). In the organic light emitting device wherein such a resonator structure is introduced, a width of a spectrum of the extracted light can be narrowed, and peak luminance can be raised, so that a color reproduction range can be expanded.
There are two kinds of this organic light emitting device: one is made of a low molecular weight material, and the other is made of a high molecular weight material. As a manufacturing method for the device made of a high molecular weight material, ink jet printing method is generally known.
However, when the organic layer is formed by the ink jet printing method, there is a problem that variation of film thickness is high. Therefore, since it is necessary to precisely control film thickness particularly when the foregoing resonator structure is introduced, there is a problem that irregular color occurs with the ink jet printing method, so that it is difficult to obtain a color reproduction range sufficient to display, for example, television picture. This problem is significant when a high molecular weight material is used for the light emitting layer.